The term "SCUBA" (an acronym for self-contained underwater breathing apparatus).

Scuba diving may be performed for a number of reasons, both personal and professional. Most people begin through recreational diving, which is performed purely for enjoyment and has a number of distinct technical disciplines to increase interest underwater, such as cave diving, wreck diving, ice diving and deep diving.

Snorkeling is a popular recreational activity, particularly at tropical resort and scuba diving locations.

The primary appeal is the opportunity to observe underwater life in a natural setting without the complicated equipment and training required for scuba diving and it appeals to all ages because of how little effort there is, and without the exhaled bubbles of scuba-diving equipment.